/*
 * Copyright 2010 Brian Watkins
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package bw.refresh;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import bw.util.*;

import com.google.appengine.api.labs.taskqueue.Queue;
import com.google.appengine.api.labs.taskqueue.QueueFactory;
import static com.google.appengine.api.labs.taskqueue.TaskOptions.Builder.*;
import static com.google.appengine.api.labs.taskqueue.TaskOptions.Method;

public class RefreshFilter implements Filter
{
    private long _lastRefreshed = 0L;
    private int _refreshMins = 1;

    public void init ( FilterConfig config ) throws ServletException
    {
        //minimum number of minutes between refresh checks
        _refreshMins = 1;
    }

    public void doFilter ( ServletRequest req, ServletResponse res, FilterChain chain )
        throws IOException, ServletException
    {
        Log.getInstance().write( "Refresh filter!" );

        long refreshMillis = _refreshMins * 60 * 1000L;
        if ( ( System.currentTimeMillis() - _lastRefreshed ) > refreshMillis )
        {
            Queue queue = QueueFactory.getDefaultQueue();
            queue.add( url( "/refresh" ).header( RefresherServlet.REFRESH_HEADER, 
                                                 "true" ).method( Method.GET ) );
            _lastRefreshed = System.currentTimeMillis();
        }

        chain.doFilter( req, res );
    }

    public void destroy ()
    {
        //nothing
    }

    
}